Generally, a headrest is mounted on an upper end of a vehicle seat to protect a user's neck or provide a comfortable surface to lean his or her head against, so that the height and angle of the headrest must be capable of being adjusted to match the physical attributes or preference of a user.
Further, the headrest plays an important role in mitigating shock to the neck due to inertia in the event of a vehicle collision. Therefore, first of all, it is important to adjust the headrest to fit a user's body. However, it is common to use the headrest without any setting because of the inconvenience of manipulation.
A conventional headrest is problematic in that it is inconvenient to use, and especially, a headrest of a back seat is simply divided into a use position and a non-use position depending on using conditions, and the headrest is always biased backwards by a spring, so that it is impossible to adjust the headrest back and forth when in use.
Furthermore, a headrest adjusted back and forth in a straight line is problematic in that a length of the lead screw corresponding to a required adjustment amount should be secured, so that a size of the headrest is inevitably increased, thus causing increase in both weight and cost. In addition, if the design of the headrest is fixed, this restricts the length of the lead screw, so that it is impossible to secure a required moving amount, thus hindering a user's convenience and vehicle roominess.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.